Process and apparatus for winding sheet material

ABSTRACT

There is provided an apparatus and process for providing the desired density and consistency characteristics in rolls of wet material - e.g., newspaper rolls, which are used in subsequent operations such as newspaper printing and where the properties of the roll are to be matched to those required during the subsequent operation.

United States Patent 1191 Mousseau [451 May 14,1974

[ PROCESS AND APPARATUS FOR WINDING SHEET MATERIAL [76] Inventor:Jean-Marie Mousseau, 6304 P. E. Lamarche, St. Leonard, Montreal 458,Quebec, Canada [22] Filed: Jan. 28, 1972 [21] Appl. No.: 221,647

[52] US. Cl. 242/66, 242/75.51 I [51] Int. Cl B65h 17/08, B65b 59/00[58] Field of Search 242/66, 67.2, 67.3 R, 75.5,

[5 6] References Cited UNITED STATES PATENTS Staege 242/66 1,838,96712/1931 Staege 242/66 X 1,987,670 1/1935 Drake 2,722,639 11/1955 Shaad242/7551 X 2,363,684 11/1944 Montgomery 242/7551 X Primary Examiner-JohnW. Huckert Assistant Examiner-Edward J McCarthy [5 7] ABSTRACT There isprovided an apparatus and process for providing the desired density andconsistency characteristics in rolls of wet material e.g., newspaperrolls, which are used in subsequent operations such as newspaperprinting and where the properties of the roll are to be matched to thoserequired during the subsequent operation.

10 Claims, 4 Drawing Figures PATENTEDIAY m an sum 1 or 2 PROCESS ANDAPPARATUS FOR WINDING SHEET MATERIAL This invention relates to anapparatus and process.

More particularly, one aspect of this invention relates to animprovement in the formation of rolls of sheet material, as for example,during the rewinding of rolls of sheet paper.

In the manufacture of various types of sheet material, such as rolls ofnewsprint paper, the sheet paper is formed by conventional techniques,which, briefly summarized, include the steps of forming a paper web froma slurry of paper-forming material (such as cellulose fibers), dryingthe web to form a dried sheet of paper and subsequently winding thedried sheet paper onto rolls.

The rolls of sheet paper when, for example, employed in newsprintoperations, must be manufactured to high tolerance requirements. Forexample, newsprint operations involve high speed processes where papermust be unwound from rolls at high speeds. Unless the quality of thepaper roll is of a certain standard, the roll of sheet paper will notrun properly during printing operations. Moreover, as is known to thoseskilled in the art, due to the different nature of machines involved innewsprint operations, different requirements for the rolls of paper haveto be provided for different types of machines in order for the roll ofpaper to perform properly.

Briefly summarized, the rolls of sheet paper must be free fromundulations and have a consistency such that the paper is capable ofbeing unwound from the roll at high speeds without breaking; andmoreover, the sheet paper rolls must not be wound so tightly as to beliable to split during transporting of the rolls. Additionally, otherrequirements for sheet paper rolls are that they must not have any flatspots i.e., where the roll is out of symmetry (it must be substantiallyperfectly cylindrical). Failure of a wound roll of sheet paper to meetthese requirements results in unacceptable rolls and hence may lead tofrequent shut down of equipment during subsequent processing operationsi.e., newsprint manufacture. Additionally, the rolls tend to split ifwound too tightly, thus rendering the rolls useless.

The roll of sheet paper as it is produced from a papermaking operationdoes not meet the above requirements and accordingly it is conventionalpractice in the art to rewind the roll to produce a tightly wound rollwhich has acceptable properties of paper tension and consistency. Tothis end, conventionally the rolls of paper from a paper-makingoperation (termed the ,parent" roll) are rewound by passing the paperover a supporting platform, subsequently passing the-paper sheet beneatha first rotatable drum (known in the art as a rear" drum) whereafter itis wound onto a core which is driven by a further spaced-apart drum(known in the art as a front drum) mounted in operative relationship tothe core onto which the paper is being rewound. Both the front and reardrums are conventionally driven at a constant speed by a common drivemeans, and both in turn frictionally drive the rewind paper core.

' Rewinding operations are nomrally high speed processes, involvingspeeds of up to 7,000 feet per minute or more. To this end, the parentroll to be rewound is mounted on a suitable supporting apparatus whichincludes a reel bar or shaft mounting the paper roll, the

reel bar being provided with a braking apparatus tied in to the driverotating the roll onto which the paper is being rewound. The brakeserves to frictionally engage the reel bar of the parent roll to arrestits rotation when and if desired depending on the speed of operation ofthe finished roll, in order to prevent paper being fed from the parentroll when rotation of the finished roll is halted. ln such operationsthe front drum is the critical component in that the torque exerted bythe front drum on the rewind roll is a major factor in determining thedensity of the finished roll throughout the rewininding process. Atpresent, conventional practices do not include torque control on therewind roll through either the front or rear drums but rather, theconventional practice uses a brake on the parent roll to control thetension on the sheet or web of paper and provide some degree of controlin the paper tension and consistency of the finished roll. This,however, provides finished rolls of a very wide latitude andinconsistency of density and it has been found that due to the lack ofocntrol, a percentage of rolls split during transportation or do nothave the desired properties for subsequent processing; nor for thatmatter, is there any uniformity between rolls so as to have constantunwind characteristics or permit the rolls to be universally'adapted foruse on each and every type of equipment employed in e.g., newspaperprinting. The importance of this will be evident when considering thecharacteristics required for a roll unwinding at, e.g., 5,000 feet fore.g., newspaper presses. Typically, finished paper rolls according toconventional practices may have a paper tension at the core of 3.5pounds per linear inch decreasing outwardly from the center of the rollto approximately 0.5 pounds per linear inch. In general, for perfectunwinding conditions at the presses, the tension of each sheet layer ofthe unwind roll (i.e., the stored tension of each layer) should beapproximately the same as the tension exerted on the sheet material asit is pulled from the unwind roll. As it is known to those skilled inthis art, lower paper tensions are encountered during initial unwindingof the roll, and increase to higher values at the center of the roll dueto greater friction by, e.g., the core rotating far faster towards theend of the unwinding operation, and with additional friction beingcreated by the friction brake normally employed. Under conventionalconditions, as previously mentioned, it is substantially impossible toattain a finished roll which matches the characteristics required duringthe complete unwinding operation and the progression of the tension fromthe above typical values i.e., from 3.5 to 0.5 pounds, is not suitablenor programmed for any and all operations.

The above limitations of the prior art are further brought out by thefact that the paper producers typically manufacture newsprint paperwhich has tensile strength of approximately 8 pounds per linear inch.This relatively high degree of tensile strength is required for, amongstother reasons, the high degree of stress to which the paper is subjectedduring unwinding at the newsprint presses. Thus, the tensile strength ofthe paper must be such that it is capable of withstanding the flutterand other vibrations as it is being unwound from the finished roll,which vibrations and flutter occur as a result of the finished roll notpossessing the required characteristics to enable it to be unwoundsmoothly at the high speeds encountered during winding. Thus, if it werepossible to provide a finished roll which had the necessary degree ofpaper tension and consistency to unwind, at high speeds in a smooth andcontinuous manner without flutter or other vibrations, the degree oftensile strength otherwise required for the paper in the finished rollcould be reduced substantially without any sacrifice in the propertiesof the paper.

With this invention, applicant has developed according to one aspect amethod and apparatus which overcomes the above deficiencies while at thesame time providing a given desired tension and consistency for rolls ofsheet material according to preselected factors, which method andapparatus are particularly adapted to the rewinding operation ofnewsprint or similar rolls, although not limited thereto.

In accordance with one embodiment of the present invention, there isprovided an apparatus suitable for forming a web of sheet material intoa roll of said sheet material having desired density and consistencycharacteristics wherein said apparatus includes means for winding thesheet material on a rotatable core, means for rotating said rotatablecore, said last-mentioned means comprising first and second spaced-apartrotatable driven means each adapted to form a nip point with sheetmaterial on said rotatable core and to rotate said rotatable corethrough frictional engagement with said sheet material wound on saidrotatable core, and separate drive means for each of said driven means,the improvement comprising variable torque control means connected inoperative relationship to one and only one of said driven means mountedin the downstream direction of movement of said sheet material, forrotating said rotatable core.

According to a further preferred form of the above embodiment, there isalso provided a paper elasticity sensor, said elasticity sensorcomprising a pair of spaced-apart rotatable rollers between which a webof paper is adapted to pass as it is being rewound from said first rollof paper into a rewind roll, said rollers comprising an upstream rollerand a downstream roller in the feed direction of the web of paper, theupstream roller being provided with braking means adapted to provide africtional brake constant, said rollers being rotatable by the movementof the web of paper, and means for measuring a difference in therelative rotation between said pair of rollers to provide an electricaloutput signal proportional to the relative speed of said rollers.According to this embodiment, the paper elasticity sensor preferablyoperates in conjunction with suitable computer means adapted to receivethe electrical signal generated by said above-mentioned means, and toprovide an electrical output signal to the torque control meansconnected to the drive means of said means for rotating said rewindpaper roll.

According to the present invention, the rewind paper roll isconventionally mounted by means of a core shaft between a pair of drivenrotatable rollers or drums termed frontf and rear" drums. The drivenrear drum is in frictional engagement with the rewind paper roll,forming a first nip point in contact therewith, between which the sheetpasses. In practice, the rewind paper roll is conventionally mounted ona core shaft and may or may not be mounted by suitable means fordisplacement of the roll during the rewinding process. The front drum,on the downstream side in the direction of feed of the web to the rewindroll, is normally a drum which frictionally drives the paper roll as itis being rewound. To this end, the drum is normally in frictionalcontact with the paper roll thereby forming a second nip point. Thefront and rear drums may be any suitable conventional type, well knownto those skilled in the art, typically being around 24 inches indiameter. Any suitable motor means may be provided for separatelydriving the front and rear drums, such as a D.C. electric motor, againwell known to those skilled in the art.

The torque control means connected to the drive means for the front drummay be of any suitable type, such torque control means being well knownto those skilled in the electrical art. To this end, the torque controlmeans is preferably of the manually or automatically adjustable type,capable of being set to provide a selected desired degree vof torquecontrol. In this manner, the front drum torque control will therebyprovide a micro-control necessary to obtain the exact required rolldensity and other characteristics in the finished roll, at any and allpoints in that roll. in the embodiment of the present invention wherethe torque control means isadapted to be manually operated, the manualoperation may include the use of a fixed cam structure mounted inoperative relationship to the torque control means for the front drumwhereby the cam means programs the increase or decrease in the torquecontrol exerted by the drive means for the front drum, which willthereby increase or decrease the tension placed on the sheet material asit is being wound to form a finished roll. In the embodiment of theinvention where the torque control means is operated in conjunction withthe elasticity sensor, the torque control means is preferably of theautomatic type responding to a predetermined signal from the sensingdevice to increase or decrease the torque requirded to provide finishedrolls having the desired degree of 'tension and consistency, ashereinafter described.

The spaced-apart rolls of the paper elasticity sensor may each be ofsimilar construction, with the exception that the upstream roller isprovided with suitable braking means as hereinafter described. Moreparticularly, each roller is freely mounted by suitable means e.g.,roller bearings and positioned by suitable frame members in the desiredline of travel of the web. To this end, the downstream roller may bedisplaceably mounted by, for example, hydraulic or pneumatic means, topermit threading of a paper web between the rollers during start-upprocedures for rewinding. Typically, each roller may be made of, forexample, fiberglass, or various types of metals e.g., aluminum andmagnesium and is preferably of a relatively light weight. To this end,the I weight of the rollers may be reduced by using hollow cylindricalrollers as opposed to solid rollers.

The diameter of the respective rollers may vary considerably and neednot be the same. Typically, in the high speed operations encounteredduring rewinding procedures, diameters of from 10 to 14 inches have beenfound to be suitable; with larger diameters being more suitable forhigher speeds and smaller diameters for slower speeds.

The width of the rollers should be at least equal to the width of theweb being rewound, and preferably is several inches greater, in order toprovide a full width support for the web. Typically, widths for suchrollers for newsprint rewinding operations vary from 127 to 369 inches,although larger or smaller diameters of course will be employed whereand as necessary.

Should different diameters of the rollers be employed, suitablecompensation will have to be provided in the output signals generated bythe rollers so as to correlate the signals to a constant factor.

Any suitable brake means may be provided for creating a desired degreeof braking action on the upstream roller to effect a differentialrotation between the upstream and downstream roller and hence provide adifferent rotational speed to the tachometer means as hereinafterdescribed. Typical of the brake means which may be employed arehydraulic or pneumatic brake means. Most desirably, the brake isconnected in a closed loop to a sensor at one end, and at the other endto a reference voltage.

As described hereinbefore, the rotatable rollers operate in conjunctionwith suitable means for generating an electrical signal proportional tothe respective speeds of the rollers. To this end, such means mayinclude, for example, fluid amplifiers, tachometer generators or similarmechanical-electrical equivalents, tachometer generators preferredbecause of thier relative simplicity and economical attributes. To thisend, the tachometer generator provides a proportional signal to thecomputer means. The computer means may be any suitable computer device,such as an analog computer, a digital computer or other equivalentcomponents. To this end, the computer means may be provided with apredetermined programmed constant (K), and is adapted to receive theoutput signal from the tachometer generator to provide a controllingsignal to the torque control means connected in operative relationshipto the drive means for the front drum device.

Preferably, according to a desired embodiment of the present invention,the generator means receives and provides a continuous output signal toprovide a constant monitoring. However, if desired, discontinuousreadings could be utilized.

As will be seen from the above description, where the torque controlmeans is employed in conjunction with the paper elasticity sensor, afinished roll can be obtained having the desired degree of tensiontogether with a desired paper elasticity factor. The significance of thepaper elasticity factor is well known to those skilled in the art, andwill become evident from the following description hereinafter. Thus,with the present invention, the desired elasticity can be built in, andin practice, maximum elasticity in the finished roll can be obtainedusing the abovedescription embodiments.

The above described process and apparatus may also be slightly modifiedand utilized for improving the quality of sheet material as the latteris formed in a parent roll. In this respect, and conventionally, in thepaper making art, sheet paper material as it is produced is passedbetween a plurality of generally vertically arranged rollers, known ascalendar rollers, whereafter it is wound onto a reel bar to form theparent roll as described above.

Formation of the parent roll by conventional practices known to thoseskilled in this art, normally involves taking-off the sheet or web sheetfrom between the lowermost pair of calendar rollers, generally termedthe queen and king rollers, passing the sheet over a driven drumrotating about a fixed axis and onto a reel bar in contact at a nippoint with the reel drum, about which the sheet material is wound.

During formation of the parent roll, the tension exerted by the reeldrum, (initially on the reel bar and subsequently on the sheet paperwound on the reel bar) at the point where the nip contact occurs withthe reel drum, represents the sole means of controlling the tension ofthe sheet paper in the parent roll. It has been found by the applicantthat this tension factor in the parent roll is not adequate for highquality parent rolls, inasmuch as the resulting parent rolls have a highdegree of susceptibility to creasing of the sheet material in the rolldue to the lack of uniform tension of the sheet material.

Additionally, since the firmness or hardness of the roll is notcontrolled, the amount of paper (in terms of its length) is notgenerally accurately known and therefore conventional practice is tomake additional paper to ensure an adequate length in the parent rollfor a subsequently rewound roll. In practice, the extra length added tothe parent roll over and above what is needed for the finished roll, isthen scrapped and put back into the paper-making operation. Stillfurther, there is no control in the production of parent rolls whichenables the qualities of the parent roll to be matched to the speed of arewinding operation, as hereinbefore described.

It is highly desirable that the tension of the parent roll besubstantially uniform; and to the extent that the prior art can providea control, this is accomplished by increasing the torque control on thereel drum of the parent roll during its formation. However, increasingthe torque control results in the loss of elasticity due to a muchhigher torque being required than is actually necessary. The loss ofpaper elasticity means that the paper roll should be used immediately,or otherwise the percentage of elasticity lost becomes so high that thepaper roll becomes unuseable. In practice, for the above reasons, it isconventional to exert only a very minor amount of torque force on thesheet material, by the reel drum at the nip point with the parent roll.Moreover, it will also be obvious that by exerting a torque force at thenip point, the pull on the web from the calendar rollers tends tostretch it, which is a reason why the elasticity factor is lost. Inother words, the stress on the sheet material was to such an extent thatas the sheet material is not of a type which readily recovers (as in thecase of a rubber-like substance), the elasticity factor is not recoveredto any extent (to some extent the elasticity recovers in the parentroll).

Thus, by prior art procedures, it is theoretically possible to obtain afirm or hard roll by increasing the tension on the paper at the nippoint formed by the reel drum and the parent roll, but this isaccomplished at the expense of elasticity. For this reason, prior artprocedures have employed only a very minor amount of torque force asexerted by the reel drum.

In accordance with this development, the above disadvantages areovercome by the hereinafter-described process. Briefly summarized, inaccordance with one aspect, in a process for forming parent rolls ofsheet material wherein the sheet material is passed over a firstrotatable drum and engaged at a first nip point by said drum and a reelbar or partially formed parent roll, the improvement is provided whereinthe tension of the sheet material is controlled in the parent roll bycausing a torque force to be exerted on said reel drum or partiallyfinished parent roll, at a point removed from said first nip pointwhereby the tension of said sheet material in said parent roll iscontrolled between said first nip point and said point at which saidtorque force is applied to said sheet material.

In accordance with this further embodiment, in an apparatus for forminga parent roll of sheet material from a supply of sheet material whereinthe apparatus includes a separately driven rotatable drum over or underwhich the sheet material is adapted to pass, and which apparatus furtherincludes a rotatable rear roller mounted in operative relationship tothe driven drum whereby a nip point is formed between which the sheetmaterial is adapted to pass, the improvements comprising a secondseparately driven rotatable drum mounted in operative relationship tosaid wheel bar whereby said second drum provides a second nip point withsaid reel bar between which said sheet material is adapted to pass afterpassing through said first nip point, and means for rotating said seconddrum and for causing said second drum to engage said reel bar with adesired amount of torque force at said second nip point.

With the above-described apparatus and process, applicant has now foundit possible to increase the tension on the paper at the nip point butwithout loss of elasticity. Thus, by applying a torque force at thesecond nip point, the tension between the two nip points is maintainedafter the sheet material is released from engagement with the second nippoint, by friction between the respective layers of the sheet materialforming the parent roll. Thus, the large area of friction between thefirst'and second nip points holds the sheet material tensioned to whatit was prior to release from the second nip point, thereby obtaining ahard or firm roll with substantially little loss in paper elasticity ascompared to prior art procedures. The loss of elasticity by the processand apparatus above described may, for example, be in the order of fromabout 2 percent to about 3 percent, compared to up to 50 percent toabout 70 percent by prior art procedures if and when employed, dependingon the atmospheric conditions prevailing at the time of manufacture ofthe parent roll.

More particularly, in the apparatus and process of the presentinvention, the provision of a second nip point utilizing a desiredtorque force, results in the formation of parent rolls of sheet materialhaving greatly improved properties for example, a substantially uniformtension with substantially crease-free paper; and with the addedadvantage that due to the uniformitylof the roll, the length of thesheet material can be more accurately gauged as compared to prior artparent rolls produced by conventional processes. Thus, by moreaccurately gauging the length of sheet material in the parent roll, thewaste factor normally associated with prior art parent rolls can bedecreased, which in turn eliminates the necessity of providing extralengths of paper in the paper roll to ensure that the rewind roll hassufficient material.

In carrying out the above process and in using the apparatus, it isconventional for the reel drum and reel bar to contact each other at anangle of anywhere from about 30 to 50, typically around 35 from thevertical axis of the reel drum, to form the first nip contact point. Inthis respect, the reel drum is conventionally driven by suitable meansknown to those skilled in the art; typically the drum serves to providea paper feed rate of between about L500 to about 2,000 feet per minute.In practice, the reel drum is mounted for rotation about a fixed axis,supported by any suitable means.

The sheet material, as it is fed to the first nip point isconventionally provided from the calendar rollers of a paper-makingoperation; it suffices to say that those skilled in the art willunderstand the conventional procedure of feeding sheet material from thecalendar rollers to the reel drum.

In conventional techniques, the sheet paper after pasisng over the reeldrum is wound onto a reel bar as explained hereinbefore. Initially,therefore, it is the surface of the reel bar itself which forms thefirst nip point with the reel drum; thereafter, the sheet malterial iswound around the reel bar, the surface layer of the wound parent rollforms the nip point. Thus, as used in this specification in, referenceto the nip point, it is to be understood that reference to the reel barwill include the situation where the sheet material on the reel barlikewise forms the nip point.

In accordance with this invention, the. second nip point is preferablyformed at a point approximately equal to one-half the circumference ofthe sheet paper travel on the reel bar, or in other words, the secondnip point is preferably formed on an axis substantially the sameas theaxis intersecting the centers of the reel drum and reel bar, to providea substantial sheet area, in the direction of travel of the sheetmaterial on the reel bar, between the first and second nip points.However, if desired, the second nip point may be spaced closer to orfurther from the preferred position of the second nip point and stillretain the advantages of the present invention.

The second nip point may be formed by employing a rotatable roller ordrum rotating about a fixed axis and driven by a suitable means such asan electric motor. The roller or drum may be mounted by any suitablemeans, such as by a central axis, and will be springloaded for movementabout a fixed path to compensate for the increased thickness of theparent roll as it is being formed. Thus, for example, the drum may bespring-loaded to maintain it in engagement with the reel bar.

Having thus generally described the invention, reference will now bemade to the accompanying drawings illustrating preferred embodiments andin which FIG. 1 is a schematic side elevational diagram of a preferredembodiment of the present invention;

FIG. 2 is a schematic diagram of the apparatus of FIG. 1 showing theconnection between the sensing device, means for generating anelectrical signal, a computer and the torque mechanism;

FIG. 3 is a schematic view of the sensing device shown in FIG. 1; and

FIG. 4 is a perspective schematic view of an apparatus according to afurther modification of the present invention.

Referring initially to FIGS. 1 to 3, there is schematically illustrateda device according to the present invention for rewinding sheet paperrolls, in conjunction with a typical rewinding operation involvingslitting of the paper.

More particularly, a roll of sheet paper 22 as would be obtained from,for example, a paper-making process, is mounted by means of a reel bar20 and suspended or positioned by suitable supporting means (not shown).The roll 22 as it comes from a papermaking operation is, relativelyspeaking, loosely wound and must be further processed to slit the sheetmaterial to a desired width. conventionally, the core shaft (reel 9 bar)20 is provided with a suitable brake mechanism to control the feed rate.

As illustrated in FIG. 1, the roll 22 is rewound into a further rollindicated by reference numeral 30 mounted on a core shaft 32, the roll30 after being processed having the desired degree of consistency andcapable of withstanding unwinding at the high speeds encountered duringsubsequent processes, or processing Operating in conjunction with therewound roll 30 is a first separately driven rear rotatable drum 34mounted on shaft 36 and a second separately driven rotatable front drum38 mounted on a shaft 40. The front drum 38 is in frictional engagementwith the paper roll 30 (thus forming a first nip point) and serves torotate roll 30 for rewinding purposes. To this end, shafts 36 and 40 areeach separately driven by a suitable motor means (not shown). Likewise,shaft 36 rotates drum 34 which is in engagement with roll 30, thusforming a second nip point. If desired, as is conventional practice inthis art, supplementary means adapted to initially aid the rotation ofthe paper roll 30 maybe provided in the form of a rider roller (notshowm). To this end, the rider roller typically engages the paper roll30 during the initial stages of formation of the roll 30.

In accordance with this invention, the power means driving the shaft 40and the drum 38 are coupled in operative relationship to a torquecontrol means 42 adapted to provide a microswitch in the power drivemeans for the shaft 40 to control the sheet density of the rewound paperroll 30. In this respect, control 42 thereby controls the torque forceand provides an additional motor control during driving or rotation ofthe roll 30 to provide the improvements in the rewound paper rollaccording to the present invention. Thus, the present invention providesa control whereby applicant may obtain 100 times or better the accuracymay obtain in providing a desired degree of tension and othercharacteristics in a finished roll as compared to any prior arttechniques.

From the above, it will be seen that by applying a torque force to thesheet material at the second nip point, the tension between the two nippoints is maintained after the sheet material W is released from thesecond nip point by the friction between the respective layers of theweb W on the roll 22.

Operating in conjunction with the above-described apparatus andaccording to one embodiment of this invention, there is provided a paperelasticity sensor. According to the embodiment illustrated, theelasticity sensor comprises a pair of rotatable rollers 50 and 52mounted in a spaced-apart relationship between which a sheet of paperindicated by reference letter W is adapted to pass from the paper roll22 as it is bein fed to the rewind roll 30. Rollers 50 and 52 arejournalled on shafts 54 and 56 respectively. Additionally, suitablebraking means are connected to roller 50, such as a hydraulic orpneumatic brake means to provide a constant brake factor.

Operating in conjunction with the elasticity sensor device is a suitabletachometer generator indicated generally by reference numeral 58,connected electrically by leads 60 and 62 to rollers 50 and 52respectively. Rotation of the rollers 50 and 52 feeds to the tachometergenerator an electrical signal proportional to the respective speeds ofthe rollers 50 and 52. Operating in conjunction with the sensing device,is a computer means 64, receiving a signal via connection 66 from thetachometer generator 58. In turn, the computer 64 feeds an input signalto the torque control device 42 based on the elasticity constant of thepaper which is being continuously monitored by the tachometer generatorand the sensing device.

By employing the sensing device as described above, there will beprovided in the finished roll, a maximum elasticity in combination withthe other attributes hereinbefore described. Thus, due to the continuoussensing of the elasticity of the paper as it is being fed to the roll22, a continuous measurement is provided (according to a preferredembodiment) which may be then translated into the finished roll asdescribed above.

The apparatus of FIG. 1, as illustrated, may be used in conjunction witha conventional slitter table indicated generally by reference numeral 26with slitters 28 slitting the paper to a desired width as it is beingwound. Guide roller 24 maybe mounted to position the web W as it isbeing fed from roll 22 to rewind roll 30.

Referring now to the embodiment as illustrated in FIG. 4, there isillustrated schematically a portion of the calendar set-upconventionallyemployed in papermaking operations as indicated by the plurality ofvertically arranged rotating rollers 100, I02, 104 and 106 which, inpractice, are journalled on rotatable shafts driven by suitable means.The lowermost pair of cooperating rollers 104 and 106 are known in theart as queen and king rollers respectively; a sheet of paper materialbeing taken-off the king roller 106. The sheet of paper material,indicated by reference letter W, is conventionally fed about a reel drum108 rotating about a fixed axis and conventionally mounted on a shaft110. The web W passes in engagement with the surface of the reel drum108, and is would about a reel bar indicated by reference numeral 112.The reel bar 112 and reel drum 108 are mounted in juxtaposition witheach other, and form a nip point indicated generally by referencenumeral 114 between which the web W passes as it is being wound onto thereel bar 112. As such, nip point 114, according to conventionalpractice, forms the only control of the tension of the sheet paper woundonto the reel bar and forming a roll 116 thereof. As explainedhereinbefore, this tension control according to prior art procedures isinadequate to provide the desired properties in a parent roll 116.

In accordance with this invention, there is provided a further drivenroller 120 mounted on a shaft 122 and rotating about a fixed axis.Roller 120 forms with the reel bar and a second nip point 124, nip point124 being located according to a preferred embodiment at a pointapproximately equal to one-half the circumference of the distance oftravel of the web W about the reel bar 112.

Although not illustrated in the schematic drawing, it will be understoodthat reel bar 112 and roller 120 are mounted by suitable means as, forexample, a mounting bracket connected to the shafts of the respectivebar 1 l2 and roller or drum 120, which mounting shafts are adapted formovement about a fixed path to compensate for the increase in thicknessof the reel bar as the paper is wound thereabout. Likewise, the mountingarms will be spring-loaded to provide a desired degree of tensionbetween the reel bar 112 and reel drum 108 at the nip point 114;likewise, in the case of roller or drum 120 and reel bar 116, the latterroller or drum 120 is preferably provided with adjustable springloadingmeans to vary the force at the nip point 124.

As will be seen from the above description, the tension applied to theweb W as it is being wound about the reel bar 112 to provide a parentroll, may be directly controlled by exerting a desired degree of forceat the nip point 124, whereby the parent roll may be wound to have adesired degree of tension. In a typical process, the tension exerted onthe web W between the nip points 114 and 124 will vary between aboutonefourth to onehalf pound per linear inch of the web, which has beenfound to produce parent rolls having improved properties for subsequentuse, particularly, for rewinding operations as described hereinbefore.However, the amount of tension may vary to higher or lower forcesdepending on the characteristics desired in the parent roll.

From the above, it will be seen that there may be obtained parent rollshaving a desired degree of elasticity combined with a desired firmness,in contrast to prior art procedures which were not capable of attaininga It will be understood that variations from the above may be madewithout departing from the spirit and scope of the invention.

1 claim: 1. In an apparatus suitable for forming a web of sheet materialinto a roll of said sheet material having desired density andconsistency characteristics wherein said apparatus comprises incombination:

means for winding the sheet material on a rotatable core, means forrotating said rotatable core, said last-mentioned means comprising firstand second spaced-apart rotatable driven means each adapted to form anip point with sheet material on said rotatable core and to rotate saidrotatable core through frictional engagement with said sheet materialwound on said rotatable core; separate drive means associated with eachof said driven means; I

and variable torque control means connected in operative relationship toone and only one of said driven means mounted in the downstreamdirection of movement of said sheet material, for rotating saidrotatable core.

2. An apparatus as defined in claim 1, wherein said apparatus includesmeans for providing a web of sheet material to be wound onto saidrotatable core, said lastmentioned means comprising a supply of saidsheet material mounted for movement about a fixed axis, elasticitysensor means for detecting the elasticity of said sheet material betweensaid supply of sheet material and said rotatable core, said variablecontrol means being responsive to said sensor means.

3. An apparatus as defined in claim 2, wherein said elasticity sensormeans comprises a pair of spacedapart rotatable rollers rotating about afixed axis, said rollers being displaced one from another in ahorizontal plane, one of said rollers having braking means associatedtherewith adapted to provide a frictional brake constant, the other ofsaid rollers being freely rotatable, and means for measuring adifferential in the relative rotation between said rollers to provide anoutput signal proportional to the relative speed of said rollers.

4. The apparatus of claim 3, wherein said apparatus includes computermeans adapted to receive said output signal, said computer means beingadapted to provide an output signal to said torque control means.

5. In a method of winding sheet material into a roll thereof havingdesired properties of tension and consistency, wherein a source of sheetmaterial is formed into a roll thereof the improvement comprisingconstantly controlling the tension of the sheet material as said roll isbeing formed by passing said sheet between a pair of spaced-apart nippoints and exerting a variable torque force on the nip point in thedownstream direction of movement of said sheet material compared to thetorque force on the nip point in the upstream direction of the movementof the sheet material.

6. A method, as defined in claim 5, wherein during winding of said sheetmaterial into a roll thereof, there is included the step of monitoringthe elasticity of said material priorto said material being wound into aroll.

7. A method as defined in claim 6, including the step of passing saidsheet material through a pair of spacedapart rollers which rotate abouta fixed axis, one of said rollers having braking means associatedtherewith and the other being freely rotatable to thereby obtain adifferential in the relative rotation between said rollers and thus toprovide an output signal proportional to the relative speed of saidrollers to determine the elasticity of said sheet material.

8. A method as defined in claim 7, including feeding said output signalto a computer means.

9. A method as defined in claim 8, wherein there is provided an outputsignal from said computer means, said last-mentioned output signalgoverning means controlling said tension imparted to said sheet materialas said roll is being formed.

10. In a method of winding sheet material into a roll thereof havingdesired properties of tension and consistency as defined in claim 5,wherein a source of sheet material is formed into a roll thereof, theimprovement comprising controlling the tension of the sheet material assaid roll is being rotated about a fixed axis, monitoring the elasticityof said material as said material is formed into said roll-by passingsaid sheet material between a pair of spaced-apart rollers rotatingabout a fixed axis, one of said rollers having braking means associatedtherewith and other being freely rotatable thereby to obtaina'differential in the relative rotation between said rollers wherebythere is obtained an output signal relative to the elasticity of saidmaterial, feeding said output signal to a computer means and controllingsaid torque relative to the material being wound to form said roll withrespect to the elasticity of said material as it is being wound inproportion to said output signal.

1. In an apparatus suitable for forming a web of sheet material into aroll of said sheet material having desired density and consistencycharacteristics wherein said apparatus comprises in combination: meansfor winding the sheet material on a rotatable core, means for rotatingsaid rotatable core, said last-mentioned means comprising first andsecond spaced-apart rotatable driven means each adapted to form a nippoint with sheet material on said rotatable core and to rotate saidrotatable core through frictional engagement with said sheet materialwound on said rotatable core; separate drive means associated with eachof said driven means; and variable torque control means connected inoperative relationship to one and only one of said driven means mountedin the downstream direction of movement of said sheet material, forrotating said rotatable core.
 2. An apparatus as defined in claim 1,wherein said apparatus includes means for providing a web of sheetmaterial to be wound onto said rotatable core, said last-mentioned meanscomprising a supply of said sheet material mounted for movement about afixed axis, elasticity sensor means for detecting the elasticity of saidsheet material between said supply of sheet material and said rotatablecore, said variable control means being responsive to said sensor means.3. An apparatus as defined in claim 2, wherein said elasticity sensormeans comprises a pair of spaced-apart rotatable rollers rotating abouta fixed axis, said rollers being displaced one from another in ahorizontal plane, one of said rollers having braking means associatedtherewith adapted to provide a frictional brake constant, the other ofsaid rollers being freely rotatable, and means for measuring adifferential in the relative rotation between said rollers to provide anoutput signal proportional to the relative speed of said rollers.
 4. Theapparatus of claim 3, wherein said apparatus includes computer meansadapted to receive said output signal, said computer means being adaptedto provide an output signal to said torque control means.
 5. In a methodof winding sheet material into a roll thereof having desired propertiesof tension and consistency, wherein a source of sheet material is formedinto a roll thereof the improvement comprising constantly controllingthe tension of the sheet material as said roll is being formed bypassing said sheet between a pair of spaced-apart nip points andexerting a variable torque force on the nip point in the downstreamdirection of movement of said sheet material compared to the torqueforce on the nip point in the upstream direction of the movement of thesheet material.
 6. A method, as defined in claim 5, wherein duringwinding of said sheet material into a roll thereof, there is includedthe step of monitoring the elasticity of said material prior to saidmaterial being wound into a roll.
 7. A method as defined in claim 6,including the step of passing said sheet material through a pair ofspaced-apart rollers which rotate about a fixed axis, one of saidrollers having braking means associated therewith and the other beingfreely rotatable to thereby obtain a differential in the relativerotation between said rollers and thus to provide an output signalproportional to the relative speed of said rollers to determine theelasticity of said sheet material.
 8. A method as defined in claim 7,including feeding said output signal to a computer means.
 9. A method asdefined in claim 8, wherein there is provided an output signal from saidcomputer means, said last-mentioned output signal governing meanscontrolling said tension imparted to said sheet material as said roll isbeing formed.
 10. In a method of winding sheet material into a rollthereof having desired properties of tension and consistency as definedin claim 5, wherein a source of sheet material is formed into a rollthereof, the improvement comprising controlling the tension of the sheetmaterial as said roll is being rotated about a fixed axis, monitoringthe elasticity of said material as said material is formed into saidroll by passing said sheet material between a pair of spaced-apartrollers rotating about a fixed axis, one of said rollers having brakingmeans associated therewith and other being freely rotatable thereby toobtain a differential in the relative rotation between said rollerswhereby there is obtained an output signal relative to the elasticity ofsaid material, feeding said output signal to a computer means andcontrolling said torque relative to the material being wound to formsaid roll with respect to the elasticity of said material as it is beingwound in proportion to said output signal.